In a mixing bowl, combine flour and powdered sugar. Cut in butter until mixture resembles coarse crumbs. Stir in egg yolk until dough forms.

Press the dough into the bottom and up the sides of a tart pan. Chill for 30 minutes.

Preheat the oven to 350°F (175°C). Bake the crust for 15 minutes or until lightly golden. Let cool.

In a saucepan, combine blueberries, sugar, and cornstarch. Cook over medium heat until the mixture starts to bubble.

In a bowl, whisk together lemon juice, eggs, and heavy cream. Gradually add to the blueberry mixture, stirring constantly.

Pour the filling into the cooled crust and bake for an additional 30 minutes or until set.

Allow the tart to cool completely before slicing. Serve chilled or at room temperature.